Methods to make a surface covering having a natural appearance

ABSTRACT

A method for making a surface covering is disclosed which includes providing a surface covering having a backing layer, a foamable layer, and a design layer, wherein the design layer includes a portion of a pattern printed with at least one retarder composition. A wear layer is then provided on the design layer and the wear layer is cured. The foamable layer is thereby expanded to form a foam layer, and the pattern printed with at least one retarder composition is chemically embossed. The cured product is subsequently cooled to ambient temperature and then the top surface of the wear layer is subjected to a sufficient temperature to soften the wear layer. After being softened the wear layer is mechanically embossed with a surface texture, the embossed surface texture is set in the wear layer, and a top coat may then be provided on the embossed set wear layer. A surface covering having the various features described above is also disclosed. Preferably, the surface covering and the method for making the surface covering have a natural wood, stone, marble, granite, or brick appearance wherein the design layer includes one or more joint or grout lines created with at least one retarder composition and the wear layer is mechanically embossed with the surface texture of a wood, stone, marble, granite, or brick surface.

This is a continuation of application Ser. No. 08/996,701, filed Dec.23, 1997, now U.S. Pat. No. 5,961,903 and claims the benefit of U.S.provisional application No. 60/039,534, filed Feb. 20, 1997, all ofwhich are incorporated herein by reference.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to surface coverings, particularly surfacecoverings having a natural appearance. The present invention furtherrelates to methods of making these types of surface coverings.

2. Description of the Related Art

A growing consumer preference for natural materials or “looks” simulatedto natural wood, stone, marble, brick, and granite now exists for alltypes of surface coverings such as flooring. The perception of naturalflooring, for instance, at an inexpensive price provides a high value,acceptable style, and luxury appearance.

The natural look of resilient vinyl floorings, for instance, made bygravure printing in conjunction with chemical embossing technology, doesnot quite impart the realistic appearance of true wood, stone, and thelike. The subtle texture of wood grains and stone cannot be achieved bychemical embossing technology which develops the texture by reacting theinhibitor in the ink with a blow agent added in a pre-gel layer underheat and during a fusion process. In general, the texture created by thechemical embossing technique does not have a well-defined sharpness ofreal, natural products. In other words, chemical embossing has thedisadvantage of being capable of making only rounded edges and there isgreat difficulty in controlling the depth of the embossing. In addition,this process leads to a texture which is too deep to be realistic.Mechanical embossing, on the other hand, is capable of reproducing thesubtile, sharp, and shallow textures of natural wood, stone, marble,brick, etc. However, embossing in register with the printed design isvery difficult with mechanical embossing.

Accordingly, there is a need for surface coverings having a realistic,natural “look” or appearance of wood, stone, marble, granite, or brickand methods of making the same.

SUMMARY OF THE INVENTION

A feature of the present invention is to provide a surface coveringhaving a design, such as, for example natural wood, stone, marble,granite, or brick, appearance which is realistic in appearance. Afurther feature of the present invention is to provide a method ofmaking such a surface covering.

Additional features and advantages of the present invention will be setforth in part in the description which follows, and in part will beapparent from the description, or may be learned by practice of thepresent invention. The objectives and other advantages of the presentinvention will be realized and attained by means of the elements andcombinations particularly pointed out in the written descriptionincluding the appended claims.

To achieve these and other advantages and in accordance with the purposeof the present invention, as embodied and broadly described herein, thepresent invention relates to a surface covering having a backing layerand a foam layer located on top of the backing layer. Further, a designlayer having a design is located on top of the foam layer. At least oneelement of the design on the design layer is chemically embossed. A wearlayer, located on top of the design layer, is mechanically embossed witha surface texture when the wear layer is in a softened state. The foamlayer may or may not be mechanically embossed. Finally, a top coat maybe located on top of the embossed wear layer.

The present invention further relates to a surface covering having anatural wood, stone, marble, granite, or brick appearance. This surfacecovering has a backing layer, a foam layer located on top of the backinglayer, and a design layer. The design layer has a design of wood, stone,marble, granite, or brick. This design layer is located on top of thefoam layer and the design has chemically embossed joint or grout lines,which simulate such features found in natural surfaces where wood,stone, marble, granite, or brick are formed as surfaces for floors, forexample. In addition, a wear layer, located on top of the design layer,is mechanically embossed with a surface texture of natural wood, stone,marble, granite, or brick after the wear layer has been softened. Thefoam layer may or may not be mechanically embossed. Finally, a top coatmay be located on top of the embossed wear layer.

The present invention also relates to a method for making a surfacecovering, preferably having a natural wood, stone, marble, granite, orbrick appearance. The method includes the steps of providing a surfacecovering having a backing layer, a foamable layer located on top of thebacking layer, and a design layer located on top of the foamable layer.The design layer preferably has a design of a wood, stone, marble,granite, or brick. A portion of the design in the design layer isprinted with a retarder composition. In the preferred embodiment, thedesign that is printed with the retarder composition is joint or groutlines. A wear layer is then provided on top of the design layer andsubjected to curing to cure the wear layer and expand the foamablelayer, thus chemically embossing areas which have been printed with theretarder composition. For purposes of the present invention, “curing” isalso known in the art as “fusing.” After curing the wear layer, it ispermitted to obtain ambient temperature. This cooled product is thensubjected to a sufficient temperature to soften the cured wear layer,preferably by heating the top suface of the cured and cooled wear layer.After it has been softened, the wear layer is mechanically embossedwhile it is in the softened state. In particular, the wear layer ismechanically embossed with a surface texture, for example, of wood,stone, marble, granite or brick and the foam layer may or may not bemechanically embossed depending on the embossed design and the pressureapplied to the wear layer.

In the preferred embodiment of the invention, the chemical embossing ofthe joint or grout lines is deeper than that of the portions of thesurface covering which have only been mechanically embossed. In thisway, the surface texture created by the mechanical embossing is limitedto the raised areas. These raised areas are the design elements of wood,stone, marble, granite, or brick, which are joined together by the jointor grout lines. Thus, the surface covering of the invention, which doesnot include mechanically embossed surface texture in the joint or groutlines, has the appearance of mechanical embossing in register, but iscreated without the technical difficulties associated with registeringmechanical embossing. Finally, in the preferred embodiment, a top coatis provided on top of the embossed wear layer.

It is to be understood that the foregoing general description and thefollowing detailed description are exemplary and explanatory only andare intended to provide further explanation of the present invention, asclaimed.

BRIEF DESCRIPTION OF THE DRAWINGS

This invention will be described in greater detail with reference to thedrawings in which:

FIG. 1 depicts a side view of the apparatus for embossing the surfacecovering of the present invention.

FIG. 2 is a fragmentary, cross-sectional view of the surface covering ofthe present invention depicting the multiple layers in detail.

FIG. 3 is a microscope photograph of the surface covering of the presentinvention.

DETAILED DESCRIPTION OF THE PRESENT INVENTION

Generally, a surface covering can be made by the present invention whichcombines chemical embossing with mechanical embossing to form a uniqueproduct. Preferably, this product is a surface covering having a naturalwood, stone, marble, granite, or brick appearance, though other surfacecoverings having the desired combination of chemical embossing andmechanical embossing as described herein form part of the presentinvention. For purposes of the present invention, surface coveringincludes, but is not limited to, flooring such as inlaid floors,hardwood floors, solid vinyl tiles, homogeneous floors, cushionedfloors, and the like; wall paper; laminates; and countertops.

In making the surface covering, a backing layer or substrate A isprovided and a foamable layer C and D is formed or placed on top ofbacking layer A as shown in FIG. 2. A design or print layer B isapplied, adhered, or located on top of the foamable layer as seen inFIG. 2. The design layer B has a design (not shown) and a portion ofthis design is formed with a retarder composition, such as, but notlimited to, a retarder ink. Preferably, the portion of the design is inthe shape and form of one or more joint or grout lines (not shown) whichsimulate, for instance, the joint lines between two strips of woodforming a surface covering or the joining of stones, marble, granite, orbrick by mortar or grout lines between each stone, marble, granite, orbrick.

Once the design layer B is applied, a wear layer is applied or locatedon top of the design layer and the surface covering, and the wear layeris then cured such as by subjecting the surface covering to heat to forma cured wear layer. This curing process will also chemically embossareas of the design layer where the retarder ink has been applied. Inthe preferred embodiment, the chemically embossed areas are the printedjoint or grout lines. Any heating means can be used, such as a gas-firedforced-hot-air oven. The product is then permitted to obtain ambienttemperature, such as by cooling. Afterwards, the surface of the productis subjected to a sufficient temperature to soften the cured wear layersurface, for instance, through re-heating, preferably by infraredradiant heat. This softens the surface in order to enable the product toreceive the mechanical embossing. The wear layer is then mechanicallyembossed to have a surface texture. Any surface texture can be embossedonto the wear layer. Preferably, the surface texture simulates or has awood, stone, marble, granite, or brick surface texture. Duringmechanical embossing, the foam layer may or may not be mechanicallyembossed. It is preferred that the foam layer is slightly embossed. Inparticular, in a preferred embodiment, the portions of the wear layerbeing mechanically embossed will compress or lose from about 1 to about4 mils in thickness while the portions of the foam layer in contact withthese portions will compress or lose from about 1 to about 5 mils inthickness. In this preferred embodiment, the total embossing depth ofwear layer and foam layer combined is between about 3 mils and about 8mils. Preferably, the foam cells within the foam layer are not crushedor collapsed in the embossed areas, but may be flattened or distorted asshown in D in FIG. 2.

A top coat (not shown in FIG. 2) may then be provided on top of theembossed wear layer to form the surface covering.

The backing layer used in the present invention can be any conventionalbacking layer used in surface coverings such as a felted or mattedfibrous sheet of overlapping, intertwined filaments and/or fibers,usually of natural, synthetic, or man-made cellulosic origin, such ascotton or rayon, although many other forms of sheets, films, textilematerials, fabrics, or the like, may be used. The substrate or backinglayer can be non-foamed, non-crosslinked vinyl compositions as well. Thethickness of a conventional substrate layer is generally not criticaland it is preferably from about 2 to about 100 mils, more preferablyfrom about 15 to about 30 mils.

The foamable layer used in the present invention can be any conventionalfoamable layer used in surface coverings, such as a foam layer used inflooring. In particular, the foamable layer can be any suitable materialknown in the art for producing foam layers such as polyvinyl chlorideplastisol or organosol. Alternatively, and preferably, the foam layer isa resilient, cellular foam layer which can be formed from a resinouscomposition containing a foaming or blowing agent that causes thecomposition to expand on heating. It is also known in the art thatfoamable, resinous sheet material can be selectively embossed bycontrolling the decomposition temperature of a catalyzed blowing orfoaming agent in the heat-expandable composition. For example, byapplying to the heat-expandable composition a reactive chemical compoundwhich is referred to in the art as a “regulator,” “inhibitor,” or“retarder,” it is possible to modify the decomposition temperature ofthe catalyzed foaming or blowing agent in the area of application of thereactive compound. It is thus possible to produce sheet materials havingsurface areas that are depressed with inhibitor application and raisedproximate the area without inhibitor application.

The inhibitor or retarder can be conveniently incorporated in aninhibitor or retarder composition, preferably in a foam-retarding,printing ink composition, which is printed over the heat-expandableresinous composition. Such compositions are well-known in the art andare generally based on an organic solvent carrier or vehicle system.Alternatively, and preferably, an aqueous retarder printing inkcomposition is used such as the one described in U.S. Pat. No.5,169,435, incorporated in its entirety by reference herein. A mostpreferred aqueous retarder printing ink composition contains from about20 to about 30% by weight acrylic resin binder, from about 6.5 to about17% by weight tolyltriazole, from about 20 to about 30% by weightalcohol, and from about 35 to about 50% by weight water. Foaming orblowing agent modifiers or inhibitors other than tolyltriazole can alsobe used including but not limited to benzotriazole, fumaric acid, malicacid, hydroquinone, dodecanethiol, succinic anhydride or adipic acid.Additionally, other foam-retarding, printing ink compositions can alsobe used, such as those described in U.S. Pat. Nos. 4,191,581 and4,083,907 to Hamilton; U.S. Pat. No. 4,407,882 to Houser; and U.S. Pat.No. 5,336,693 to Frisch, all incorporated in their entirety by referenceherein.

In the present invention, for purposes of creating the foamable layer,which is chemically embossed, a substrate comprising an expandableresinous layer containing a foaming or blowing agent is provided. Aprinted design is provided over at least a portion of the expandableresinous layer. At least a portion of this printed design comprises aretarding composition. As will be described in further detail below,once a wear layer is applied on top of the foamable layer, theexpandable resinous layer (e.g., the foamable layer) is then subjectedto a sufficient temperature for a sufficient time to expand the layerand thereby form an embossed region of the layer proximate the portionof the printed design that contained the foaming or blowing agentmodifier or inhibitor. Generally, a sufficient temperature is from about195° C. to about 215° C. and for a time of from about 2.5 minutes toabout 3.0 minutes to create the foam layer.

Prior to subjecting the expandable resinous layer and design layer toheat, a wear layer is deposited or applied on top of the design layerand the layers, along with the substrate, are subjected to heat orcuring which will not only cure the wear layer, but also expand theresinous layer and cause chemical embossing as described earlier.

The portion of the design layer which does not comprise at least oneretarder composition is formed by non-retarder ink compositions. Anexample of such an ink composition contains an acrylic resin, water,alcohol, and one or more pigments. In forming a design having both aretarder composition and one not containing a retarder composition, sucha design can be done in register using multiple station rotogravureprinting. As indicated earlier, in the preferred embodiment of thepresent invention, a design layer contains a pattern of joint or groutlines which are created with at least one retarder composition. Uponexpansion of the foamable layer, these portions will be chemicallyembossed and will visually form joint or grout lines to simulate suchlines which exist with natural wood, stone, marble, granite, or bricksurfaces. The joint or grout lines created with the retarder compositiongenerally will have a width of, for example, from about 1/16 inch toabout ¼ inch.

The wear layer can be made of any suitable material known in the art forproducing such wear layers. Preferably, the wear layer is a transparentpoly(vinyl chloride) layer. The dry film thickness of this PVC layer isnot critical and it is preferably from about 5 mils to 50 mils, and morepreferably from about 10 mils to about 20 mils. Other examples of thiswear layer include, but are not limited to, acrylic polymer,polyolefins, and the like.

As indicated, this wear layer is applied to and adhered to the foamablelayer. Means to apply the wear layer to the foamable layer are known inthe art and include, but are not limited to, a reverse-roll coater. Oncethe wear layer is applied to the top of the foamable layer, the wearlayer is cured. This curing can be accomplished by subjecting the wearlayer along with the foamable layer and substrate to a sufficienttemperature, e.g., by heating, to cure the wear layer in a multi-zonegas-fired hot air oven essentially as described in U.S. Pat. No.3,293,108. Also, the curing or heating step will expand the foamablelayer to form the foam layer which will have chemically embossed areas.For purposes of curing the wear layer, a sufficient temperature for asufficient time would be used and known to those skilled in the art.Preferably, this temperature is from about 195° C. to about 215° C. fora time of from about 2.0 minutes to about 3.0 minutes, more preferablyabout 2.0 minutes to about 2.2 minutes.

Once the wear layer is cured, it is preferred to permit the wear layerto obtain an ambient temperature, such as by passing it over a series ofwater-cooled drums or “cans” essentially as described in U.S. Pat. No.3,293,108. The wear layer is then subjected to a sufficient temperaturefor a sufficient time in order to soften the wear layer to a sufficientdegree to allow it to be mechanically embossed. The surface temperatureof the wear layer for purposes of mechanically embossing it ispreferably from about 145° C. to about 160° C. depending on, among otherthings, the color of the printed design under the wear layer surface.The mechanical embossing of the wear layer can be achieved in such amanner that the foam layer beneath the wear layer may or may not bemechanically embossed. In any event, the portion of the the foam layerwhich has been overlayed with the design layer having the retardercomposition is not mechanically embossed. And, the portions or areas ofthe foam layer beneath the areas or portions of the wear layer that areembossed are generally slightly embossed. For purposes of the presentinvention, any embossing technique known to those skilled in the art canbe used; for example, the product can be fed through a nip between anengraved steel embossing roll and a rubber back-up roll, such that theface of the wear layer is in contact with the engraved steel roll. SeeFIG. 1. The embosser gap can “float” against a fixed pressure, or morepreferably the embosser gap can be “fixed” by adjustable steel “wedgeblocks” for example. However, the fixed gap approach requires thatcareful attention be paid to maintaining consistent caliper of theproduct prior to entry into the embosser section of the process. Thepreferred starting point for the fixed gap is 60% of the specificproduct caliper. Fine-tuning adjustments can then be made to achieve thespecified appearance. Furthermore, in order to maintain faithfulreproduction of the embossing roll engraving in the embossed surfacecovering, it is advantageous to maintain some positive tension or “draw”on the web as it enters the nip. This tension also helps to keep the webtracking straight.

For purposes of mechanical embossing, generally, the pressure applied tothe wear layer is sufficient to create an embossing of, for example,from about 1 mil to about 12 mils, more preferably from about 3 mils toabout 8 mils. As indicated earlier, in the preferred embodiment of thepresent invention, the chemical embossing of the joint or grout lines isdeeper than that of the portions of the surface covering which have onlybeen mechanically embossed. This process, which does not create themechanically embossed surface texture in the joint or grout lines,imparts to the surface covering the appearance of mechanical embossingin register.

It is certainly within the bounds of the present invention to useseveral devices to mechanically emboss different textures onto the wearlayer. In the preferred embodiment of the present invention, the deviceused to mechanically emboss will have a pattern that will simulate thesurface texture of wood, stone, marble, granite, or brick and thistexture will be transferred onto the wear layer.

In accordance with the invention and as shown in FIG. 1, a cured, foamedand cooled surface covering is processed as follows to produce a surfacehaving a “natural” appearance. A web of cooled cushioned covering ispassed through the “WEB GUIDE” at the point indicated by the entryarrow. This “WEB GUIDE” is provided to insure that the web tracksstraight through the embosser nip. After exiting the “WEB GUIDE”, theweb passes under the five burners of the “IR HEATER”. The heat output ofthe “IR HEATER” is adjusted as necessary to properly heat the surface ofthe web by adjusting the height of the burners above the web, and byadjusting the gas flow to the burners. From the “IR HEATER” the webproceeds to the “EMBOSSER”. The hot surface of the web contacts anengraved steel embossing roll. The embossing nip, mentioned above,consists of this engraved steel embossing roll and a rubber bed roll,which contacts the back surface of the web. The rubber bed roll isprovided with a steel back-up roll which can be used, if necessary, tocounteract any tendency of the rubber roll to “bow” downward. The web ismaintained in contact with the water-cooled embossing roll for about 90degrees of wrap by means of the uppermost idler roll. This contact withthe cooled embossing roll surface removes some of the heat from thesurface of the web by heat transfer from the web sheet to thewater-cooled steel embossing roll, and thus “sets” the embossing. Thedwell time is dependent on exact embossing roll circumference and linespeed and can be easily determined by one skilled in the art.Approximate dwell time ranges are given for three possible web speeds inTable I below.

TABLE I Web Speed (ft./min.) Dwell Time Range (seconds) 48 1.6-1.8 601.3-1.4 70 1.1-1.2The cooled embossed web is then directed back under the “IR HEATER”section of the apparatus. At the point indicated by the exit arrow, theweb continues on to a final coating station (not shown) for applying atop-coat to the surface of the web as described below. The apparatus forthis coating station is well known to those skilled in the art.

As indicated above, a critical feature of the invention is the surfacetemperature of the web at the exact instant when the web sheet entersthe embossing roll nip. This temperature is dependent on the thicknessof the layer, the speed of the moving web, and the exact position wherethe measurement is taken. However, this exact spot is not generallyaccessible for temperature measurements because of the diameter of theembossing roll. Normally, therefore, the reading is taken from themid-point of the distance between the end of the IR heater and theembossing roll nip. The actual temperature as the web sheet enters theembossing roll nip will be lower than this reading because of heat lossfrom the web sheet surface as it moves through the space between themeasurement point and the embossing roll nip. The faster the line speed,the less opportunity for heat loss and the closer the actual temperaturewill be to the measured temperature at the embossing nip.

A guide for temperature ranges based on web speed and layer thicknessfor vinyl is given below in Table II. It should be remembered, however,that the ability of a surface to absorb heat from IR energy isdependent, among other things, on the color of that surface. Thus, theexact temperature within the preferred range will depend on thepredominate color of the sheet being embossed. Therefore, theseconditions are starting conditions only, and fine tuning adjustments canbe made as needed to achieve the product appearance specified by the“standard sample”. In fact, in some instances, it may be necessary tooperate outside the preferred ranges discussed above to achieve theproduct appearance specified by the “standard sample”.

TABLE II clear vinyl caliper web speed (ft./min.) temperature range ° C..019″ 48 155-160 .014″ 60 150-155 .012″ 70 145-150

Once the wear layer is mechanically embossed, a top coat, also known asa wear layer top coat, is applied to the top and adhered to the embossedwear layer. The top coat can be composed of any suitable material knownin the art for this purpose. Preferably, the top coat is a urethane topcoat. Once the top coat is applied, the overall surface coveringcontaining all of the layers is cured. Preferably, the top coat has athickness of from about 0.5 mil to about 2.0 mils, more preferably, fromabout 0.9 mil to about 1.3 mils.

Optionally, besides the layers discussed above, one or more additionallayers can be present, such as the layers described in U.S. Pat. No.5,458,953, incorporated in its entirety by reference herein. Suchadditional layers include strengthening layers, additional foamablelayers, and a wear layer base coat. The composition of these layers andtheir locations are described in U.S. Pat. No. 5,458,953 and can be usedin the surface covering of the present invention.

As indicated earlier, the present invention also relates to a surfacecovering as seen in the photograph of FIG. 3. This surface covering hasa backing layer A, a foam layer C and D applied on top and adhered orattached to the backing layer. A design layer B having a design isprinted on the foam layer. At least a portion of the design layerincludes a chemically embossed pattern. Preferably, this chemicallyembossed pattern is in the shape and form of joint or grout lines aspreviously described. A wear layer is applied on top of the design layerand this wear layer is mechanically embossed with a surface texture. Thefoam layer C and D may or may not be mechanically embossed. The surfacetexture is preferably the texture of wood, stone, marble, granite, orbrick. Finally, a top coat or wear layer top coat (not shown in FIG. 3)is applied on top of and adhered to the embossed wear layer. The detailsof each of these components is described above.

As also indicated, additional optional layers such as those described inU.S. Pat. No. 5,458,953 can be incorporated into this surface covering.Such additional optional layers include a strengthening layer, a wearlayer base coat, and/or additional foam layers.

The present invention will be further clarified by the followingexamples, which are intended to be purely exemplary of the presentinvention.

EXAMPLE 1

A cushioned vinyl floor covering having a backing, a foam layer with achemically embossed texture in the foam, and a clear vinyl layer wasprepared essentially as described in U.S. Pat. No. 3,293,108, hereinincorporated by reference in its entirety.

The backing was a felted fibrous sheet of the type that is customarilyused for substrate layer in this type of floor covering. In thisexample, the backing thickness was 0.025 inches (±0.001 inches). Thefoam layer was formed from a plasticized polyvinyl chloride compositioncontaining a foaming or blowing agent. The foamable PVC plastisol hadbeen solidified or “gelled” by heating. A design was printed on thesurface of the solidified PVC composition, using pigmented inks such asare customarily used in this process. One or more of the inks containeda reactive chemical compound commonly referred to as a “retarder.”Detailed information concerning the chemical retardation of chemicallyfoamed PVC plastisols, as well as an example of formulations for bothplastisols and inks, can be found in a journal article by Andrew Hunter,“Cellular Polymers,” Vol. 2, pp. 241-249 (1983) (Applied SciencePublishers, Ltd., Essex, England), herein incorporated by reference inits entirety. In this example, the foam layer was 0.035 inches (±0.003)thick in the areas that were not chemically retarded.

The clear vinyl layer was formed from a PVC plastisol which was coatedonto the printed solidified (“gelled”) foamable PVC compositionfollowing the printing of the design. The clear vinyl layer was cured,and the foamable vinyl composition foamed, by heat. During thisoperation, the chemical embossing was formed by action of the retarderchemical contained in certain inks. The heat was supplied by amulti-zone gas-fired hot air oven with zones operating between about195° C. and about 215° C. Residence time in the oven was about 3minutes. An example of a formulation for the clear vinyl can be found inthe journal article by A. Hunter (cited above). In this example, theclear vinyl layer was 0.019 inches (±0.001 inches) thick. Furthermore,the areas that were printed with ink containing a retarder compound,specifically joint or grout lines, had chemical embossing that was aminimum of about 0.010 inches in depth.

The vinyl flooring material described above was cooled and thenmechanically textured in the following manner.

The material was heated by passing it under a gas-fired infrared radiantheater delivering approximately 360 BTU/sq. ft./min.; at a product speedof 37 ft./min. (±2 ft./min.). The heater was positioned between about3.5 inches and about 6.0 inches above the material surface, depending onthe color of the decorative print. The ability of a surface to absorbheat from infrared energy is dependent on such factors as the color ofthe decorative print. As is well known in the art, the heat delivered bythe gas-fired infrared heater described above can be fine-tuned byadjusting the gas-flow controls so that the sheet surface temperature ismaintained within the preferred range as given below.

The surface temperature of the material exiting from the heater wasapproximately between 150° C. and 160° C., as measured by a non-contactIR pyrometer held approximately 12-18 inches from the material surface.The back surface of the substrate felt layer was approximately between80° C. and 85° C., as measured by “stick-on” heat tape (for example,“Thermolable,” supplied by Paper Thermometer Co., Inc. of Greenfield,N.H.).

The heated material was then passed through an embossing nip between anengraved steel roll and a rubber back-up roll. The nip was set at 0.050inches (±0.005 inches) for the material described above. The nip openingwas set by adjustable steel “wedge blocks.” Clamping pressure wassufficient so that the nip opening did not vary (“float”) while thematerial was passing through the nip.

The steel roll had an embossing texture engraved onto it by means thatare well known in the art. The rubber back-up roll was approximately90-95 durometer (Shore A). Both rolls were water-cooled such that thesurface of the engraved steel roll was approximately 26° C. to 38° C.,as measured by a contact thermocouple pyrometer.

Following the embossing nip, the material was directed by idler rolls sothat it wrapped about one quarter of the engraved roll circumference.The additional contact of material against the water-cooled engravedroll was provided in order to cool the vinyl surface and “set” theembossed texture.

As the final step in preparing a surface covering having a “natural”appearance, the material was coated with a urethane acrylate top coat ofthe type that was cured by actinic radiation in the UV wavelengthregion.

The coating was applied to yield a cured thickness approximately between0.0009 inches and 0.0012 inches. The application was such that thecoating followed the embossing texture and did not significantly reducethe embossing depth of the texture. The embossing depth of themechanical texture in the finished product was between about 0.003inches and approximately 0.008 inches depending on the specific engravedroll used. However, regardless of the specific engraved roll used, thereis no mechanically embossed surface texture in the chemically embossedareas because the minimum chemical embossing depth of about 0.010 inchesis deeper than the maximum depth of the mechanically embossed surfacetexture of about 0.008 inches.

The surface gloss (or “shine”) of actinic radiation cured acrylatedurethane surface coatings can be varied in a controlled manner toproduce the desired visual effect consistent with a “natural”appearance. In one specific example, the appearance of a printed brickdesign was made more natural by use of a coating with a flat panel 60degree gloss of about 40 unit.

These actinic radiation cured acrylated urethane coatings are readilyavailable from several commercial suppliers including, but not limitedto, Lord Corporation, Erie, Pa.

EXAMPLE 2

A cushioned vinyl floor covering having a backing, a foam layer with achemically embossed texture in the foam, and a clear vinyl layer wasprepared as described in Example 1. This vinyl flooring material wascooled and then mechanically textured in the following manner.

The material was heated by passing it under a gas-fired infrared radiantheater delivering approximately 360 BTU/sq. ft./min.; at a product speedof 48 ft./min. (±2 ft./min.). The heater was positioned between about3.5 inches and about 5.0 inches above the material surface, depending onthe color of the decorative print. As is well known in the art, the heatdelivered by the gas-fired infrared heater described above can befine-tuned by adjusting the gas-flow controls so that the sheet surfacetemperature is maintained within the preferred range as given below.

The surface temperature of the material exiting from the heater wasapproximately between 155° C. and 160° C., as measured by a noncontactIR pyrometer held approximately 12-18 inches from the material surface.The back surface of the substrate felt layer was approximately between80° C. and 85° C., as measured by “stick-on” heat tape (for example,“Thermolable,” supplied by Paper Thermometer Co., Inc. of Greenfield,N.H.).

The heated material was then passed through an embossing nip between anengraved steel roll and a rubber back-up roll. The nip was set at 0.050inches (±0.005 inches) for the material described above. The nip openingwas set by adjustable steel “wedge blocks.” Clamping pressure wassufficient so that the nip opening did not vary (“float”) while thematerial was passing through the nip.

The steel roll had an embossing texture engraved onto it by means thatare well known in the art. The rubber back-up roll was approximately90-95 durometer (Shore A). Both rolls were water-cooled such that thesurface of the engraved steel roll was approximately 26° C. to 38° C.,as measured by a contact thermocouple pyrometer.

In order to maintain an embossed image that is an accurate reproductionof the engraved surface, a positive “draw” was maintained on the webusing the embossing roll driver operated at a DC current flow of +6amperes. This “draw” also assisted in maintaining proper alignment ofthe web tracking, and minimizing side-to side wandering.

Following the embossing nip, the material was directed by idler rolls sothat it wrapped about one quarter of the engraved roll circumference.The additional contact of material against the water-cooled engravedroll was provided in order to cool the vinyl surface and “set” theembossed texture.

The final step of coating the material with a urethane acrylate top coatwas performed as in Example 1 to yield a cured thickness approximatelybetween 0.0009 inches and 0.0012 inches with an embossing depth of themechanical texture in the finished product being between about 0.003inches and approximately 0.008 inches depending on the specific engravedroll used.

Other embodiments of the present invention will be apparent to thoseskilled in the art from consideration of the specification and practiceof the invention disclosed herein. It is intended that the specificationand examples be considered as exemplary only, with a true scope andspirit of the invention being indicated by the following claims.

1. A method of making a surface covering having multiple layersincluding a wear layer comprising: chemically embossing at least aportion of a first layer, subsequently mechanically embossing at least aportion of a second layer, wherein the first layer is disposed below thesecond layer and a chemically embossed portion of the first layer has adepth greater than any embossed portion of the second layer, and whereinsaid second layer is said wear layer, and applying said wear layerbefore chemical embossing.
 2. The method according to claim 1, whereinthe wear layer has uniform melt viscosity and is cured during chemicalembossing.
 3. The method according to claim 1, wherein the wear layercontains no reactive compounds that would lead to chemical embossing. 4.The method according to claim 1, wherein the mechanically embossedportion of the wear layer does not include the chemically embossedportion.
 5. The method of claim 1, wherein said first layer comprisesfoam and the chemical embossing comprises the step of expanding saidfoam.
 6. The method of claim 1, wherein said mechanical embossing occurswhen said second layer is in a softened state.
 7. The method of claim 1,wherein said first layer is a foam layer.
 8. The method of claim 1,wherein the mechanical embossing achieves an emboss depth of about 1 toabout 12 mils.
 9. The method of claim 7, wherein the total embossingdepth of the wear layer and foam layer combined is about 3 to about 8mils.
 10. The method of claim 7, wherein the foam layer comprises foamcells beneath the mechanically embossed portion of the wear layer whichare not crushed or collapsed.
 11. The method of claim 7, wherein atleast a portion of the foam layer that is chemically embossed is notmechanically embossed.
 12. A method of making a floor covering,comprising: a) providing a surface covering comprising a backing layer;a foamable layer; and a design layer containing at least one retardercomposition in at least a portion thereof and in contact with saidfoamable layer; b) providing a wear layer and curing said wear layer,thereby expanding said foamable layer to form a foam layer andchemically embossing that portion of said foam layer in contact withsaid retarder composition; and c) subsequently mechanically embossing asurface texture onto said wear layer, wherein a chemically embossedportion of said foam layer has an emboss depth greater than the embossdepth of any portion of said mechanically embossed portion.
 13. Themethod of claim 12, further comprising the step of softening said wearlayer by subjecting it to a temperature sufficient to soften it prior tosaid mechanical embossing step.
 14. The method of claim 13, furthercomprising the steps of curing and subsequently cooling said wear layerto reduce its temperature to approximately ambient temperature prior tosaid softening step.
 15. The method of claim 13, wherein said softeningstep includes subjecting said wear layer to a sufficient softeningtemperature of about 195° C. to 215° C.
 16. The method of claim 12,wherein the mechanical embossing achieves an emboss depth of about 1 toabout 12 mils.
 17. The method of claim 12, wherein the total embossingdepth of the wear layer and foam layer combined is about 3 to about 8mils.
 18. The method of claim 12, wherein the foam layer comprises foamcells beneath the mechanically embossed portion of the wear layer whichare not crushed or collapsed.
 19. The method of claim 12, wherein atleast a portion of the foam layer that is chemically embossed is notmechanically embossed.
 20. The method according to claim 12, wherein themechanically embossed portion of the wear layer does not include thechemically embossed portion.